A study of four weight loss diets that emphasise protein, fat or carbohydrate. Subjects were overweight adults (n=81) and were randomly assigned to one of four diets providing %energy from fat, protein and carbohydrate in different amounts (20, 15 & 65%; 20, 25 & 55%; 40, 15 & 45%; and 40, 25 & 35% respectively). At six months, subjects had lost an average of 6kg (&% of initial body weight), but began to regain weight after 12 months. By two years, weight loss was similar in those on the 15% protein diet and those on the 25% protein diet. It was also similar in those on the 20% fat and 40% fat diets; and in those on the 65% carbohydrate and 35% carbohydrate diets (P>0.2 for all comparisons). The two low-fat diets and the highest-carbohydrate diet reduced LDL cholesterol levels more than did the high-fat diets or the lowest-carbohydrate diet (low-fat vs. high-fat, P=0.001; highest-Cho vs. Lowest-CHO, P=0.01). The lowest-carbohydrate diet increased HDL levels more than did the highest-carbohydrate diet (P=0.02). All diets reduced triglyceride levels to a similar extent.
March 2009